Investigation of the thermal expansion and heat capacity of the Ca[Cu.sub.3][Ti.sub.4][O.sub.12] ceramics

The thermal expansion of the Ca[Cu.sub.3][Ti.sub.4][O.sub.12] ceramics has been measured over a wide temperature range 120-1200 K. The high quality of the samples under study has been confirmed by good agreement of the results of measurements of the heat capacity in the range 2-300 K and in the vicinity of the phase transition of magnetic nature at 25 K with the data for the single crystal. No anomalies in the thermal expansion that can be associated with the phase transition at 726-732 K assumed by other investigators have been found. The influence exerted on the thermal expansion by the heat treatment of the sample in a helium atmosphere and in air has been investigated.